The present invention relates to a cooling apparatus for directly or indirectly cooling electronic elements such as MPUs.
FIG. 9 to FIG. 11 of U.S. Pat. No. 5,910,694 show a cooling apparatus having a structure in which air is exhausted or discharged from one side of a heat sink. In many of conventional cooling apparatuses improvement was made on the impeller with a plurality of blades of an axial flow fan which sucks air from one side of the axial direction and exhausts the air to the other side of the axial direction. The improvement was made in such manner that the fan may discharge as much air as possible in the radial direction. In this type of conventional cooling apparatuses, the impeller with a plurality of blades is rotated by a motor in an opening defined in a case body which constitutes an air duct.
In conventional cooling apparatuses the diameter of the impeller is smaller than the diameter of the opening of the case body and the blades are rotating inside the opening. To increase the air flow of conventional cooling apparatuses it is necessary to increase the speed of the motor. However, there is a limitation to the increase of air flow which can be achieved by increasing the speed of the motor and also there arises a problem of noise getting larger.
It is an object of the present invention to provide a cooling apparatus which can increase air flow without increasing the speed of the motor. It is another object of the present invention to provide a cooling apparatus with reduced noise.
A cooling apparatus of the present invention comprises a case body having a first wall part with an opening through which air is sucked in, a base having a second wall part which faces the first wall part defining a space between the first wall part and the second wall part, an impeller having a plurality of blades which rotate inside the opening, and a motor for rotating the impeller. The case body is fixed to the base. Air is sucked in through the opening and discharged through and outside said space. According to the present invention, the blades are provided with extending portions at the ends thereof which are integrally formed with blades and rotate in said space. According to the present invention, it is possible to stir up the stagnant air in the space between the first wall part and the second wall part and to discharge the air vigorously outside from the discharge port. Therefore it is possible to increase air flow without increasing the speed of the motor.
An embodiment of a cooling apparatus according to the present invention comprises a case body having a first wall part with an opening through which air is sucked in, a base having a second wall part which faces the first wall part defining a space between the first wall part and the second wall part, wherein the case body is fixed to the base, a peripheral wall part disposed between the first wall part and the second wall part surrounding said space so as to leave a discharge port which communicates with said space, an impeller with a plurality of blades which rotate inside the opening, and a motor for rotating the impeller, and a plurality of webs holding the motor by connecting the housing of the motor and the first wall part. The revolving shaft of the motor is positioned such that its axis extends in a direction which is perpendicular to a direction in which the first wall part and the second wall part extend. The revolving shaft is supported by a bearing which is fixed to the housing in such a structure that the shaft will not come off from the bearing. Air sucked in through the opening is discharged from the discharge port. In this case also blades are provided with extending portions at the ends thereof which extend outward in the radial direction of the shaft and rotate in the space which is outside and surrounds the opening. The extending portions of the blades are integrally formed with the blades.
It is preferable that the edges of extending portions of the blades which face the first wall part and extend along the first wall part are sloped so as to be gradually away from the first wall part as they extend toward the ends. In this way the noise generated due to the air flow between the blades and the first wall part can be made smaller and thus it is possible to reduce the noise.
It is preferable to define the inside shapes of the first wall part and the second wall part so that the cross-section area of a portion of the space adjacent to the discharge port becomes larger as it approaches toward the discharge port. In this way pressure loss around the exit can be minimized and the reduction of air flow can be avoided.
A variety of structures can be used for a base and a heat sink itself can be used as a base.